This invention relates generally to threading and forming methods and apparatus for accomplishing these tasks and, more specifically, to such threading and forming apparatus which enables one to simultaneously form and thread a piece of stock at a single work station of a four slide machine.
A great variety of manufactured products require various lengths of rod or the like to be formed to an irregular contour and have one or more ends thereof provided with threads, such as for the attachment of the rod member to some other part of mechanism. Such items are particularly common on automotive vehicles, finding applications in the form of interconnecting linkages such as throttle controls and shifting linkages, or as fastening devices such as spare tire or battery hold-downs. Even some common hardware items such as "U" bolts or other types of anchor bolts are generally within this category, all of which generally require threads to be provided on at least one end thereof.
In one method of manufacturing such items utilized by many small job shops, suitable stock is first cut to the desired length by any suitable means such as on a shear or the like. Next, the workpieces are transferred to a threading machine either manually or by automated machinery, where the threads are formed thereon normally by means of a conventional die which cuts the threads into the workpiece. Generally, the machines employed in the threading operation are not adapted to handle workpieces which are not straight, thus requiring the threading operation be performed prior to any shaping of the workpiece. Thereafter, the threaded workpieces are transported to a four slide machine or other forming machine for shaping into the desired finished contour. As the threads are already formed on the workpiece, care must be taken in the design of the forming tooling to avoid damage thereto. Often these products, such as various types of linkages and the like used in the production of automobiles, are fabricated by relatively small job shops which may not have both threading and forming machinery, thus requiring the parts be transported between separate manufacturing facilities. Even should all the machinery be available at the one location, automated feed equipment between this machinery will most likely not be available due to the limited production runs generally encountered and the substantial investment required. Thus, the workpieces must be manually transported from one machine to the next. Even assuming a fully automated operation, the necessity of performing these operations sequentially substantially increases the time required to transform raw stock into the finish products and, thus, also increases the cost of such products. These time and cost factors are significantly magnified when the product is a high volume item such as generally encountered in production of parts for the automotive industry as well as such common hardware items as eye bolts, "U" bolts, anchor bolts and the like.
Accordingly, the present invention provides a method and apparatus by which a four slide machine may be adapted to simultaneously form and thread a workpiece thus allowing substantial reductions in production time and associated costs as well as minimizing material handling requirements. The apparatus includes a thread rolling head and motor for driving the same, both of which are mounted on a compound slide which is, in turn, movably secured to the four slide machine. The lower slide member is provided with a cam follower which engages a cam on the four slide machine to reciprocate the threading apparatus into and out of engagement with the workpiece. An upper slide member allows the threading apparatus to move longitudinally with respect to the lower slide member. In operation, a continuous length of stock is automatically fed into the four slide machine and a predetermined length is severed therefrom. A first forming tool means is advanced to clamp the workpiece just prior to its being severed from the supply stock. Thereafter, other forming tooling is advanced to engage and shape a portion of the workpiece simultaneously with the advancement and operation of the threading apparatus. The operational sequencing of both the threading apparatus and forming tooling is controlled by a plurality of cams conventionally provided on four slide machines. Upon completion of the threading and forming operations, all of the tooling is retracted and the completed product is ejected or otherwise removed from the machine thus completing the operational cycle.
The finished product is not only produced more quickly and at lower cost but additionally is superior in that the present invention rolls the threads on the product as opposed to conventional operations which generally cut the threads. Rolled threads necessarily have superior strength characteristics due to the hardening effect created by cold working the metal. Further, the present invention allows a small machine shop specializing in forming operations which may not have threading machinery to readily adapt an existing four slide machine to perform threading operations with a relatively small capital investment as compared with the purchase of separate automated threading apparatus.
Other features and advantages of the present invention will become apparent from the subsequent description and the appended claims taken in conjunction with the accompanying drawings.